This invention relates generally to a method for activating an anti-pinch system.
Vehicle power window regulators are often equipped with a device for detecting an obstruction during the closing movement of a window. The detection of the obstruction during the closing movement of the window generally depends on monitoring the behavior of one of the state variables of the motor, such as the current or the rotating speed of the motor.
During the shifting movement of the window and for a constant supply voltage, the speed or the current of the motor is representative of the motor load and the resistance exerted by the window. An obstruction is detected during the closing movement of the window if the behavior of the current or the speed differs from a normal behavior. In this case, the motor is stopped or even reversed.
A problem is that when the window drive motor is started, the speed or the current is not representative of the load on the motor. In the event that there is backlash in the mechanism, the speed of the motor increases very rapidly during start-up, then decreases before stabilizing. The current of the motor, after the initial inrush current, decreases very rapidly, then increases before stabilizing. The particular behavior of the current and the speed when the motor is started produces the detection by the device of the fictitious presence of an obstruction and the stopping or reversal of the movement of the motor.
To prevent this risk when the motor starts, the obstruction detection systems are activated only after a delay relative to the start-up of the motor. The criterion for delaying the activation of the obstruction detection systems is, for example, a time criterion or a criterion linked to the number of motor revolutions already completed.
The drawback is that the criteria adopted for delaying the activation of the anti-pinch systems is inaccurate and lead to a substantial risk of pinching of the obstruction if the obstruction is already present in the path of the window close to an upper edge of the window.
A need therefore exists for a more accurate activation of obstruction detection systems in the path of an openable member of a vehicle such as a window or the like to reduce the pinching force when an obstruction is present on start-up.